A common and widespread application of position-measuring devices is in numerically controlled machine tools. In such machine tools, position-measuring devices are used to determine instantaneous position values which are needed by subsequent electronics, such as a numerical control system, to calculate setpoints for control circuits used to control the feed rate of a tool or workpiece. For this purpose, rotary encoders or angle-measuring devices are directly or indirectly coupled, for example, to the shaft of a motor, and length-measuring devices are coupled, for example, to a movable tool carriage.
Modern position-measuring devices generate digital absolute measurement values, which may be both position values and measurement values that are derived from the variation with time of position values, such as, for example, velocity or acceleration values. Also known are position-measuring devices which additionally acquire measurement values from sensors, such as temperature or vibration sensors, located inside or outside the position-measuring device. Transmission of the measurement values from the position-measuring device to the subsequent electronics is via digital data transmission interfaces. For an example of a position-measuring device of the above-mentioned type having a digital data transmission interface, reference is made here to EP 0 660 209 A1. Another digital data transmission interface for data transmission between a position-measuring device and subsequent electronics is disclosed in WO 2009/149966 A1. In order to provide the necessary functions (acquiring position signals, processing the position signals into digital position values or measurement values derived therefrom, communicating with the subsequent electronics), complex analog and digital circuit blocks are needed.